Patents by Inventor Inwoong Kim

Inwoong Kim has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 8989581
    Abstract: An optical network for reassigning a carrier wavelength of an optical signal may include first and second optical nodes. The first optical node may be configured to transmit an optical signal along an optical path. The first optical node may also be configured to tune a carrier wavelength of the optical signal from a first wavelength to a second wavelength, according to a continuous function, to reassign the carrier wavelength of the optical signal. The second optical node may be configured to receive the optical signal and may include a feedback loop configured to adjust a wavelength of a reference optical signal to approximate the carrier wavelength of the optical signal.
    Type: Grant
    Filed: March 22, 2012
    Date of Patent: March 24, 2015
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Paparao Palacharla, Xi Wang, Motoyoshi Sekiya
  • Patent number: 8989571
    Abstract: According to an aspect of an embodiment, a method of modulating supervisory data onto an optical signal includes increasing a first power level of a first polarization component of an optical signal based on supervisory data. The method further includes decreasing a second power level of a second polarization component of the optical signal based on the supervisory data. The decrease in the second power level is substantially the same as the increase in the first power level such that a total power of the optical signal is substantially constant.
    Type: Grant
    Filed: September 14, 2012
    Date of Patent: March 24, 2015
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Olga Vassilieva, Paparao Palacharla, Motoyoshi Sekiya
  • Patent number: 8989595
    Abstract: Methods and systems for mitigating degradation of an optical signal-to-noise ratio (OSNR) induced by polarization dependent loss (PDL) in an optical network include determining an increase in power (?P) corresponding to a PDL-induced decrease in OSNR for a given channel being transmitted over an optical signal transmission path. The increase in power (?P) may be adjusted for at least some of the network nodes in the optical signal transmission path. At certain network nodes, the increase in power (?P) may be realized with a combination of attenuation and gain.
    Type: Grant
    Filed: June 19, 2013
    Date of Patent: March 24, 2015
    Assignee: Fujitsu Limited
    Inventors: Olga Vassilieva, Inwoong Kim, Motoyoshi Sekiya
  • Patent number: 8983290
    Abstract: Systems and method for monitoring an optical power of a dual-polarization signal are disclosed. The systems and methods may include measuring a first parameter set associated with a supervisory signal, the supervisory signal being communicated in-band with the dual-polarization signal; calculating a second parameter set from the first parameter set; calculating an intensity value from the second parameter set, the intensity value associated with one of the polarization states of the dual-polarization signal; and estimating a signal power associated with the supervisory signal from the intensity value.
    Type: Grant
    Filed: June 24, 2013
    Date of Patent: March 17, 2015
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Olga Vassilieva, Paparao Palacharla, Motoyoshi Sekiya, Jeng-Yuan Yang
  • Patent number: 8977137
    Abstract: An apparatus including a polarization controller is described. The polarizer controller is communicatively coupled via a feedback loop to an evaluation module located near an optical receiver. The evaluation module is configured to measure polarization dependent loss (PDL) of an optical signal received at the optical receiver. The polarization controller is configured to receive feedback control data regarding the PDL from the evaluation module. Additionally, the polarization controller is configured to modify a state of polarization of the optical signal at an optical transmitter, which is communicatively coupled to the optical receiver, based on the feedback control data.
    Type: Grant
    Filed: July 18, 2012
    Date of Patent: March 10, 2015
    Assignee: Fujitsu Limited
    Inventors: Olga Vassilieva, Inwoong Kim, Motoyoshi Sekiya
  • Patent number: 8942114
    Abstract: A system and method are provided for monitoring traffic in a network comprising a plurality of links, wherein each of the plurality of links comprises a plurality of neighboring pairs of slots. The system and method may include identifying a first usage status and a second usage status, calculating a utilization entropy value based at least on the difference between the first and second usage status, iteratively calculating a set of utilization entropy values for a portion of the network, and calculating an overall utilization entropy value for the portion of the network under analysis based at least on a statistical analysis of the set of utilization entropy values.
    Type: Grant
    Filed: June 21, 2011
    Date of Patent: January 27, 2015
    Assignee: Fujitsu Limited
    Inventors: Xi Wang, Inwoong Kim, Qiong Zhang, Paparao Palacharla, Motoyoshi Sekiya
  • Publication number: 20140376908
    Abstract: Systems and method for monitoring an optical power of a dual-polarization signal are disclosed. The systems and methods may include measuring a first parameter set associated with a supervisory signal, the supervisory signal being communicated in-band with the dual-polarization signal; calculating a second parameter set from the first parameter set; calculating an intensity value from the second parameter set, the intensity value associated with one of the polarization states of the dual-polarization signal; and estimating a signal power associated with the supervisory signal from the intensity value.
    Type: Application
    Filed: June 24, 2013
    Publication date: December 25, 2014
    Inventors: Inwoong Kim, Olga Vassilieva, Paparao Palacharla, Motoyoshi Sekiya, Jeng-Yuan Yang
  • Publication number: 20140376907
    Abstract: Methods and systems for mitigating degradation of an optical signal-to-noise ratio (OSNR) induced by polarization dependent loss (PDL) in an optical network include determining an increase in power (?P) corresponding to a PDL-induced decrease in OSNR for a given channel being transmitted over an optical signal transmission path. The increase in power (?P) may be adjusted for at least some of the network nodes in the optical signal transmission path. At certain network nodes, the increase in power (?P) may be realized with a combination of attenuation and gain.
    Type: Application
    Filed: June 19, 2013
    Publication date: December 25, 2014
    Inventors: Olga Vassilieva, Inwoong Kim, Motoyoshi Sekiya
  • Publication number: 20140369679
    Abstract: Methods and systems for asymmetrically compensating degradation of an optical signal-to-noise ratio (OSNR) induced by polarization dependent loss (PDL) in dual-polarization optical system include using an OSNR compensator. The OSNR compensator may separate the dual-polarization components and determine which component has degraded OSNR. The degraded component may be OSNR compensated using a phase-sensitive amplifier and/or a regenerator with a phase-sensitive amplifier.
    Type: Application
    Filed: June 18, 2013
    Publication date: December 18, 2014
    Inventors: Olga Vassilieva, Inwoong Kim, Jeng-Yuan Yang, Motoyoshi Sekiya
  • Publication number: 20140363164
    Abstract: Methods and systems for mitigating effects of polarization dependent loss (PDL) in an optical network transmitting a multi-carrier optical signal comprising a plurality of subcarriers may involve assigning and modifying a state of polarization to each subcarrier prior to transmission. An assigned state of polarization for each subcarrier may be modified for the subcarrier in the digital domain and/or the optical domain. Various specific assignment methods may be used, including individual subcarrier assignment, subcarrier set assignment, arbitrary subcarrier group assignment, random assignment, and/or combinations thereof. The assigned states of polarization may be selected based on a resulting minimum PDL-induced peak-to-peak power variation over a sum of the subcarriers for all orientations of a principal axis of PDL.
    Type: Application
    Filed: June 10, 2013
    Publication date: December 11, 2014
    Inventors: Inwoong Kim, Olga Vassilieva, Paparao Palacharla, Motoyoshi Sekiya
  • Patent number: 8909063
    Abstract: A method for regenerating and amplifying optical signals includes determining a source optical signal, adding a first pump optical signal and a second pump optical signal to the source optical signal to yield an intermediate optical signal, duplicating the intermediate optical signal to yield a first duplicate signal and a second duplicate signal, phase-shifting the first duplicate signal, passing the phase-shifted first duplicate signal and the second duplicate signal bi-directionally through a nonlinear optical element, and performing degenerate phase-sensitive amplification on the phase-shifted first duplicate signal and the second duplicate signal.
    Type: Grant
    Filed: October 31, 2012
    Date of Patent: December 9, 2014
    Assignee: Fujitsu Limited
    Inventors: Jeng-Yuan Yang, Youichi Akasaka, Motoyoshi Sekiya, Inwoong Kim
  • Patent number: 8909049
    Abstract: In accordance with embodiments of the present disclosure, a method may include determining individual spectrum requirements for each of a plurality of signals to be communicated in an optical network, wherein a first signal of the plurality of signals has a first spectrum requirement and a second signal of the plurality of signals has a second spectrum requirement. The method may also include calculating a minimum spectrum granularity based on the individual spectrum requirements. The method may further include assigning each particular signal a channel spectrum equal to an integer multiple of the minimum spectrum granularity.
    Type: Grant
    Filed: July 1, 2011
    Date of Patent: December 9, 2014
    Assignee: Fujitsu Limited
    Inventors: Xi Wang, Qiong Zhang, Inwoong Kim, Paparao Palacharla, Motoyoshi Sekiya
  • Patent number: 8909062
    Abstract: A method for regenerating optical signal includes determining a source optical signal to be regenerated, adding a first pump optical signal and a second pump optical signal to the source optical signal to yield an intermediate optical signal, creating a first conjugate optical signal and a second conjugate optical signal from the intermediate optical signal, and performing degenerate phase-sensitive amplification utilizing the first conjugate optical signal, the second conjugate optical signal and the source optical signal to yield an output optical signal. The source optical signal is modulated with a multilevel modulation format. Each conjugate optical signal has a phase that is a conjugate of a multiple of the phase of the source optical signal.
    Type: Grant
    Filed: June 18, 2012
    Date of Patent: December 9, 2014
    Assignee: Fujitsu Limited
    Inventors: Jeng-yuan Yang, Youichi Akasaka, Motoyoshi Sekiya, Inwoong Kim
  • Publication number: 20140233965
    Abstract: A system includes an optical power meter operable to generate an optical power signal corresponding to the optical power of a received output signal generated by an optical IQ-modulator. The system further includes a processor operable to receive the optical power signal and determine, based on a minimization algorithm and the received optical power signal, a first bias voltage to be applied to a first sub-modulator of the optical IQ-modulator and a second bias voltage to be applied to a second sub-modulator of the optical IQ-modulator. The system may also include a peak power meter operable to generate a peak power signal corresponding to the peak power of the received output signal generated by the optical IQ-modulator, wherein the processor is further operable to determine, based on a minimization algorithm and the received peak power signal, a third bias voltage to be applied to a phase shift component of the optical IQ-modulator.
    Type: Application
    Filed: February 21, 2013
    Publication date: August 21, 2014
    Applicant: Fujitsu Limited
    Inventors: Inwoong Kim, Olga Vassilieva, Paparao Palacharla, Motoyoshi Sekiya
  • Publication number: 20140226971
    Abstract: A method for adjusting an optical signal includes determining a polarization dependent loss (PDL) value associated with the optical signal, determining an angle between the optical signal and one or more axes of PDL, determining an amount of nonlinear phase noise due to PDL and nonlinear effects upon the optical signal based upon the PDL value and the angle, determining a phase rotation based upon the amount of nonlinear phase noise, and applying the phase rotation to the optical signal.
    Type: Application
    Filed: February 8, 2013
    Publication date: August 14, 2014
    Applicant: FUJITSU LIMITED
    Inventors: Olga Vassilieva, Inwoong Kim, Motoyoshi Sekiya
  • Patent number: 8798481
    Abstract: In accordance with embodiments of the present disclosure, a method for compensation of noise in an optical device is provided. The method may include calculating noise present in an optical carrier signal. The method may also include generating quadrature amplitude modulation input signals, the quadrature amplitude modulation input signals each including a term for compensation of the noise based on the calculated noise. The method may further include modulating the optical carrier signal to generate a modulated optical signal based on quadrature amplitude modulation input signals.
    Type: Grant
    Filed: December 14, 2010
    Date of Patent: August 5, 2014
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Olga I. Vassilieva
  • Patent number: 8761600
    Abstract: According to an aspect of an embodiment, a method of modulating supervisory data onto an optical signal includes receiving supervisory data and adjusting a characteristic of a carrier of the optical signal for at least one of a first polarization component of the optical signal and a second polarization component of the optical signal based on the received supervisory data. The characteristic may be adjusted such that there is a relative difference between the characteristic for the first polarization component and the second polarization component. The relative difference of the characteristic between the first polarization component and the second polarization component may indicate the supervisory data. Alternately, the characteristic may be adjusted such that there is a change in a polarization orientation of the carrier on a Poincaré sphere that indicates the supervisory data.
    Type: Grant
    Filed: September 14, 2012
    Date of Patent: June 24, 2014
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Olga Vassilieva, Paparao Palacharla, Motoyoshi Sekiya
  • Publication number: 20140119743
    Abstract: A method for regenerating and amplifying optical signals includes determining a source optical signal, adding a first pump optical signal and a second pump optical signal to the source optical signal to yield an intermediate optical signal, duplicating the intermediate optical signal to yield a first duplicate signal and a second duplicate signal, phase-shifting the first duplicate signal, passing the phase-shifted first duplicate signal and the second duplicate signal bi-directionally through a nonlinear optical element, and performing degenerate phase-sensitive amplification on the phase-shifted first duplicate signal and the second duplicate signal.
    Type: Application
    Filed: October 31, 2012
    Publication date: May 1, 2014
    Applicant: FUJITSU NETWORK COMMUNICATIONS, INC.
    Inventors: Jeng-Yuan Yang, Youichi Akasaka, Motoyoshi Sekiya, Inwoong Kim
  • Publication number: 20140099102
    Abstract: A method of statistical sharing in an optical communications network is disclosed. The method includes identifying a peak transmission rate and a base transmission rate for each of a plurality of client interface cards of an optical node. The method further includes provisioning a set of universal transceivers of a plurality of universal transceivers for a particular client interface card of the plurality of client interface cards such that the combined bandwidth of the set of universal transceivers is greater than or equal to the base transmission rate of the particular client interface card. The method also includes reserving one or more shared universal transceivers of the plurality of universal transceivers for the particular client interface card, when a transmission rate of the particular client interface card exceeds the base transmission rate of the particular client interface card.
    Type: Application
    Filed: May 9, 2013
    Publication date: April 10, 2014
    Applicant: Fujitsu Limited
    Inventors: Xi Wang, Qiong Zhang, Inwoong Kim, Paparao Palacharla, Motoyoshi Sekiya
  • Publication number: 20140079390
    Abstract: According to an aspect of an embodiment, a method of modulating supervisory data onto an optical signal includes increasing a first power level of a first polarization component of an optical signal based on supervisory data. The method further includes decreasing a second power level of a second polarization component of the optical signal based on the supervisory data. The decrease in the second power level is substantially the same as the increase in the first power level such that a total power of the optical signal is substantially constant.
    Type: Application
    Filed: September 14, 2012
    Publication date: March 20, 2014
    Applicant: FUJITSU LIMITED
    Inventors: Inwoong KIM, Olga VASSILIEVA, Paparao PALACHARLA, Motoyoshi SEKIYA